Green’s Dictionary of Slang

barking dogs n.

also barking fidos
[a pun on SE; note dogs n.1 (1)]

(US) aching or sore feet.

D. Burley in Chicago Defender 7 Nov. 6: They do have ‘barking Fidos’ which yelp in pain and anguish as their owners ‘tread the shorts’.
[US]T.J. Farr ‘The Language of the Tennessee Mountain Regions’ in AS XIV:2 89: barking dogs. Aching feet.
[US]Wentworth & Flexner DAS.